My father-in-law's gateway recently started making a lot of noise and now won't turn on. I removed the power supply. Is there a way to tell what kind of power supply this is (format type) and if it is broken? If it is broken, does newegg sell a unit that is compatible with it? Is the small green led on the motherboard adjacent to the battery related to the power supply functionality.

Are there certain dimensions that make the power supply a micro vs. standard in size?

A standard ATX PSU is 5.9" x 3.3" on the side that has the power cord and screw holes.

AFAIK there is no "official micro ATX" size. The one SKORPI0 linked is an SFX size. However, most people don't know about anything other than ATX, so vendors (and many consumers) incorrectly references them as "micro ATX."

For instance at Newegg you can find "micro ATX" as well as "SFX12V" power supplies as two different categories. They are the same thing. Thanks, Newegg, for creating confusion. Either categorize them properly (as SFX, they even used to have different SFX and SFX12V) or improperly (all "micro ATX"), but don't split up PSUs and list half with each.

Even more retarded is their "mini ITX" listing, which used to be called (maybe more properly) "flex ATX." Why did they change what they called them?

Here's some food for thought. Which "mini ITX" cases at Newegg use these PSUs that Newegg lists as "mini ITX?" I can't find any. Closest is the Antec ISK 300-150, but that is a proprietary PSU similar in size, but not an exact fit without modding.

Same goes for "micro ATX." Well, at least with "micro ATX" there might be some that do, for instance the Pixxo slim cases use them (SFX) and in the past Athenatech slim cases used them. However, the Rosewill and Apex slim cases use TFX PSUs, and all the cube and mini towers use ATX PSUs.

Simple way to test basic functionality is to short the purple wire on the motherboard connector with any ground (black) wire. This is NOT a 100% guarantee, as it just shows you the PSU is not completely dead. Also, some PSUs won't run this way even if they are fine.

__________________The best way to future-proof is to save money and spend it on future products. (Ken g6)

Simple way to test basic functionality is to short the purple wire on the motherboard connector with any ground (black) wire. This is NOT a 100% guarantee, as it just shows you the PSU is not completely dead. Also, some PSUs won't run this way even if they are fine.